Female cats don't have testicles, which means the owner has misjudged the cat's sex. Cats with testicles are male, and the owner can take the cat to a veterinary hospital for professional identification. 
Female cats typically only have a vagina and anus, which are located close to each other. Male cats have anus, testicles, and penis, which are separate. After three months of age, the testicles of male cats gradually migrate from the abdominal cavity into the scrotum.
When buying a cat, be careful not to believe the seller's description of its gender; it's best to verify the gender yourself.
